Coal liquefaction

ABSTRACT

Insoluble material is separated from a coal liquefaction product by use of a promoter liquid having a 5 volume percent distillation temperature of at least 250* F., most preferably at least 400* F. and a 95 volume percent distillation temperature of at least 350* F. and no greater than about 750* F. The liquid has a characterization factor of at least 9.75. By use of the promoter liquid, insoluble material can be effectively separated from the coal product by a gravity settling technique. A preferred gravity settling apparatus is also disclosed.

United States Patent Sze et al. Dec. 24, 1974 COAL LIQUEFACTION3,791,956 2/1974 Gorin et al 208/8 M l [75] Inventors gg f zf z g g g 1:J Primary Examiner-Charles N. Hart Assistant ExaminerRobert G. Mukai[73] Assignee: The Lummus Company, Bloomfield, Attorney, Agent, orFirm-Mam &.Jangarathis 22 Filed: Nov. 7, 1972 [571 1 ABSTRACT I l fInsoluble materia is separated from a coa ique ac [211 Appl' 304519 tionproduct by use of a promoter liquid having a volume percent distillationtemperature of at least 52 U.S. c1 210/73, 208/8, 208/ 2 most preferablyat least and a [51] Int. Cl Cl0g l/00 lime percent i l i n mper ure f atleas 350 [58] Field of Search 208/8, 10, 210/73, R and g r than abOlltThe liqui as 21 210/33, 202 characterization factor of at least 9.75. Byuse of the promoter liquid, insoluble material can be effectively [56]References Cit d separated from the coal product by a gravity settlingUNITED STATES PATENTS technique. A preferred gravity settling apparatusis 3,519,553 7/1970 Johanson et al. 208/10 also dlsclosed' 3,687,8378/1972 Fiocco et al. 208/8 31 Claims, 2 Drawing Figures 26 \lMake Up 1To 550 F (425500Fl 2/ 1 23 25 l /3 l 24 J a 0 Cool slurrying H\ Liqzefaggtlon Separation I V sesglc i ildn Recovery m 6y00 -900 F /0 2 /5/7 22 1" 900F+ l Stripping 1 COAL LIQUEFACTION This invention relates tothe liquefaction of coal, and more particularly to the de-ashing of acoal liquefaction product.

Coal can be converted to valuable products by sub jecting coal tosolvent extraction, with or without hydrogen, to produce a mixture ofcoal extract and undissolved coal residue, including undissolvedextractable carbonaceous matter, fusain and mineral matter or ash.

The finely divided mineral matter or ash and unreacted coal must beseparated from the coal extract, and in general, this separation stephas been the principal drawback to the successful operation of a coalextrac tion process. The fine particle sizes encountered in coalsolvation processes create numerous difficulties in attempting to useconventional separation techniques, such as filtration, centrifugationor settling. Attempts to use filtration techniques have not beenparticularly successful as a result of plugging of the filter pores withor without a precoat and the expense involved in providing the requiredfiltration area.

Gravity settling techniques have also met with limited success as aresult of low settling rates and inefficient ash removal. Centrifugationtechniques have also been generally unsuccessful as a result of highcost and the difficulty in separating the lighter finely dividedmaterials.

Accordingly, there is a need for an effective process for separatingfinely divided insoluble material from a coal liquefaction product.

An object of the present invention is to provide for improved coalliquefaction.

Another object of the present invention is to provide a new and improvedprocess for separating finely divided insoluble material from a coalliquefaction product.

A further object of the present invention is to provide a process forseparating insoluble material from a coal liquefaction product whichdoes not require a filtration step.

Still another object of the present invention is to provide an improvedgravity settler for coal deashing.

These and other objects of the present invention should be more readilyapparent from reading the following detailed description thereof withreference to the accompanying drawing wherein:

FIG. 1 is a simplified schematic flow diagram of a coal liquefactionprocess incorporating the teachings of the present invention; and

FIG. 2 illustrates a preferred embodiment of a gravity settler for coaldeashing.

The objects of the present invention are broadly accomplished, in oneaspect, by use of a liquid which promotes and enhances the separation ofinsoluble material from a coal liquefaction product. More particularly,the coal liquefaction product, comprised of a liquid coal extract ofdissolved carbonaceous matter in a coal liquefaction solvent andinsoluble material (ash and unreacted coal) is mixed with a liquidpromoter having an aromaticity less than that of the liquefactionsolvent to enhance and promote the separation of insoluble material andprovide a liquid coal extract essentially free of insoluble material.

The liquid which is employed to enhance and promote the separation ofinsoluble material from the coal liquefaction product is generally ahydrocarbon liquid wherein T is the molal average boiling point of theliquid R); and G is specific gravity of the liquid (60 F/60 F).

The characterization factor is an index of the aromaticity/parafinicityof hydrocarbons and petroleum fractions as disclosed by Watson & NelsonInd. Eng. Chem. 25 880 (I933), with more parafinic materials havinghigher values for the characterization factor (K). The promoter liquidwhich is employed is one which has a characterization factor (K) inexcess of 9.75 andwhich is also less aromatic than the liquefac tionsolvent; i.e., the characterization factor K of the promoter liquid hasa value which is generally at least 0.25, higher than thecharacterization factor of the liquefaction solvent.

The following Table provides representative characterization Factors (K)for various materials:

The liquid which is used to enhance and promote the separation ofinsoluble material is further characterized by a 5 volume percentdistillation temperature of at least about 250 F. and a volume percentdistillation temperature of at least about 350 F. and no greater thanabout 750 F. The promoter liquid preferably has a 5 volume percentdistillation temperature of at least about 310 F. and most preferably ofat least about 400 F. The 95 volume percent distillation temperature ispreferably no greater than about 600 F. The most preferredpromoterliquid has a 5 volume percent distillation temperature of at least about425 F. and a 95 volume percent distillation temperature of no greaterthan about 500 F. It is to be understood that the pro moter liquid maybe a hydrocarbon; e.g., tetrahydronaphthalene, in which case the 5volume percent and 95 volume percent distillation temperatures are thesame; i.e., the hydrocarbon has a single boiling point. In such a case,the boiling point of the hydrocarbon must be at least about 350 F. inorder to meet the requirement of a 5 volume percent distillationtemperature of at least about 250 F. and a 95 volume percentdistillation temperature of at least about 350 F. The promoter liquidispreferably a blend or mixture of hydrocarbons in which case the 5volume percent and 95 volume percent distillation temperatures are notthe same.

The 5 volume and 95 volume percent distillation temperature may beconveniently determined by ASTM No. D 86-67 or No. D 1160 with theformer being preferred for those liquids having a 95 percent volumedistillation temperature below 600 F. and the latter for those above 600F. The methods for determining such temperatures are well known in theart and further details in this respect are not required for a fullyunderstanding of the invention. It is also to be understood that thereported temperatures are corrected to atmospheric pressure.

As representative examples of such liquids, there may be mentioned:kerosene or kerosene fraction from paraffinic or mixed base crude oils;middle distillates, light gas oils and gas oil fractions from paraffinicor mixed based crude oils; alkyl benzenes with side chains containing ormore carbon atoms; paraffmic hydrocarbons containing more than 12 carbonatoms; white oils or white oil fraction derived from crude oils;alphaolefms containing more than 12 carbon atoms; fully hydrogenatednaphthalenes and substituted naphthalenes; propylene oligomers (pentamerand higher); tetrahydronaphthalene, heavy naphtha fractions, etc. Themost preferred liquids are kerosene fractions; white oils; fullyhydrogenated naphthalenes and substituted naphthalenes; andtetrahydronaphthalene.

The amount of liquid promoter used for enhancing and promoting theseparation of insoluble matter from the coal liquefaction product willvary with the particular liquid employed, the coal liquefaction solvent,the coal used as starting material and the manner in which theliquefaction is effected. As should be apparent to those skilled in theart, the amount of liquid promoter used should be minimized in order toreduce the overall costs of the process. It has been found that by usingthe liquid of controlled aromaticity, in accordance with the teachingsof the present invention, the desired separation of insoluble materialmay be effected with modest amounts of liquid promoter. In general, theweight ratio of liquid promoter to coal solution may range from about0.221 to about 3.0: 1, preferably from about 0.3:1 to about 2.0:] and,most preferably from about 0.311 to about 1.521. In using the preferredpromoter liquid of the present invention which is a kerosene fractionhaving 5 percent and 95 percent volume distillation temperatures of 425F. and 500 F. respectively, promoter liquid to coal solution weightratios in the order of 0.4:1 to 0.611 have been particularly successful.It is to be understood, however, that greater amounts of liquid promotermay be employed, but the use of such greater amounts is uneconomical. Inaddition, the use of an excess of liquid promoter may result in theprecipitation or separation of an excessive amount of desired coalderived products from the coal extract. More particularly, as the amountof liquid promoter employed is increased, a greater amount of ash isseparated from the coal solution, but such an increased separation isaccompanied by an increased separation of desired coal derived productsfrom the coal solution. By using the liquid promoters of the presentinvention, not only may modest amounts of solvent be employed, but, inaddition, ash may be effectively separated from the coal solution; e.g.,in amounts greater than 99 percent, without an excessive loss of desiredcoal derived products.

More particularly, coal, such as bituminous coal, on a moisture ash freebasis (MAF) may contain from about 5 percent to about 10 percent ofinsoluble material, such as fusain, and accordingly, at a minimum, fromabout 5 percent to about 10 percent, of the MAF coal, is lost in theprocess. In the recovery of coal derived products by a solvationprocess, the potential product loss is measured by the amount of 850 F+product which is not recovered from the coal in that it is thisfraction, which includes insoluble coal material, such as fusain, whichcan not be recovered from the residual solid product of the coaldeashing. In accordance with the present invention, on a MAF coal feedbasis, product loss of 850 F+ components (on an ash free basis) can bemaintained at a value of no greater than about 40 percent, by weight,and preferably no greater than about 25 percent, by weight. In general,the loss of 850 F+ products, on a MAF coal basis, is from about 10percent to about 25 percent, by weight. In addition, the net coalproduct (the extracted carbonaceous matter, excluding promoter liquid,liquefaction solvent and gas make), hereinafter sometimes referred to ascoal product, contains less than about 1 percent insoluble material,generally less than 0.1 percent insoluble material and most preferablyless than 0.05 percent insoluble material, all by weight. The specificamount of insoluble material which is permitted to be present in thecoal product is dependent upon the product standards, and the deashingis controlled in order to provide the required specifications. Based onan Illinois type, the production of a coal product having less than .05percent, by weight, insoluble material, corresponds to 99+ percent ashremoval but as should be apparent to those skilled in the art, thepercent ash removal to provide a coal product having the requiredminimum amount of insoluble material is dependent upon the initial ashcontent of the coal. Thus, in accordance with the present invention, theliquid promoter is added to the coal solution in an amount, ashereinabove described, to provide a coal product in which insolublematerial is present in an amount of less than about 1 percent, byweight, and most preferably of less than 0.05 percent, by weight, withthe loss of 850 F+ product being from about 10 percent to about 40percent, by weight, preferably from about 10 percent to about 25percent, by weight, on a MAF coal feed basis; i.e., from about 60percent to about percent, by weight, of the MAP coal feed is recoveredas either gas make or liquid fuel product.

The liquid promoter may also be prepared by blending a material having acharacterization factor below 9.75 with a material having acharacterization factor about 9.75, provided the blend has acharacterization factor about 9.75 and the boiling properties, ashereinabove described. The use of blended materials is a convenientmanner of regulating the characterization factor.

The separation of the insoluble material from the coal extract isgenerally effected at a temperature from about 300 F. to about 600 F.,preferably from about 350 F. to about 500 F., and at a pressure fromabout 0 psig to about 500 psig, preferably at a pressure from about 0psig to about 300 psig. It is to be understood that higher pressurescould be employed, but as should be apparent to those skilled in theart, lower pressures are preferred. The insoluble material is preferablyseparated by gravity settling with the essentially insolublefree coalextract being recovered as an overflow and the insoluble material asunderflow. In such gravity settling, the amount of underflow should beminimized in order to minimize the loss of heavier products in theunderflow. The underflow withdrawal rate to obtain desired results isdeemed to be within the scope of those skilled in the art. In general,such a rate is from about 20 to about 25 wt. percent of the total feed(liquefaction product and promoter liquid.) The residence time for suchsettling is generally in the order of from about 0.5 to about 6 hours,and preferably from about 0.5 to 3.0 hours.

In accordance with a particularly preferred embodiment of the presentinvention, the coal liquefaction product, prior to mixing thereof withthe promoter liquid, is treated to separate at least those componentsboiling up to about the 95 volume percent distillation temperature ofthe promoter liquid. In this manner, the coal liquefaction product isfree of components which boil within the range of those present in thepromoter liquid, thereby facilitating the subsequent recovery of thepromoter liquid from the coal liquefaction product.

The invention will be further described with respect to an embodimentthereof illustrated in the accompanying drawing. It is to be understood,however, that the scope of the invention is not to be limited thereby.

Referring to the drawing, ground or pulverized coal, generallybituminous, sub-bituminous or lignite, preferably bituminous coal, inline 10 is introduced into a coal solvation and slurrying zone 11 alongwith a coal liquefaction solvent in line 12. The coal liquefactionsolvent may be any one of the wide variety of coal liquefaction solventsused in the art, including both hydrogen donor solvents, non-hydrogendonor solvents and mixtures thereof. These solvents are well known inthe art and, accordingly, no detailed description thereof is deemednecessary for a full understanding of the invention. As particularlydescribed, the coal liquefaction solvent is a 600-900 F. solvent whichis recovered from the coal liquefaction product and which has not beensubjected to hydrogenation subsequent to the recovery thereof. Thesolvent is added to the coal in an amount sufficient to effect thedesired liquefaction, and in general, is added in an amount to provide asolvent to coal weight ratio from about 1:1 to about :1, and preferablyfrom about 1.5:1 to about 5:1.

A coal paste is withdrawn from zone 11 through line 13 and introducedinto a coal liquefaction zone 14 wherein, as known in the art, the coalis converted to liquid products. The liquefaction zone 14 is operated asknown in the art and may be catalytic or non-catalytic and may beeffected in the presence or absence of added hydrogen. The hydrogenationmay be effected in a fixed catalyst bed, fluidized catalyst bed or in anexpanded or ebullating bed. The details of the coal liquefaction stepform no part of the present invention and, accordingly, no detailsthereof are required for a full understanding of the invention. Asparticularly described, the coal liquefaction is effected in thepresence of added hydrogen. The hydrogenation, as known in the art,increases the recovery of coal products and also reduces the sulfur andnitrogen content of the recovered liquid coal product. The liquefactionis preferably effected in an upflow ebullated bed, as known in the art;e.g., as described in US. Pat. No. 2,987,465 to Johanson. The coalliquefaction zone, as known in the art, includes means for recoveringthe various gaseous products.

A coal liquefaction product, comprised of a liquid coal extract ofdissolved carbonaceous matter in the coal liquefaction solvent andinsoluble material (ash and undissolved coal) is withdrawn from theliquefaction zone 14 through line 15 and introduced into a separationzone 16 to separate from the coal liquefaction product at least thosematerials boiling up to about the volume percent distillationtemperature of the liquid to be used for promoting and enhancing theseparation of the insoluble material. The separation zone 16 may includean atmospheric or vacuum flashing chamber or tower, and as particularlydescribed separation zone 16 is designed and operated to separatecomponents boiling up to about 550 F.

A coal liquefaction product, free of components boiling up to about 550F., withdrawn from separation zone 16 through line 17, is mixed withpromoter liquid in line 21 of controlled aromaticity, i.e., thecharacter ization factor of the promoter liquid has a value which isgenerally at least 0.25 unit greater than the characterization factor ofthe coal liquefaction solvent. As particularly described, the promoterliquid is a kero sene fraction which has 5 volume percent and 95 volumepercent distillation temperatures which fall within the range from about425500 1F and is derived from a naphthenic or paraffinic distillate.

The combined stream of coal liquefaction product and promoter liquid inline 22 is introduced into a gravity separation zone 23, comprised of agravity settler which may be any one of those known in the art, whereinan essentially solids free overflow is separated from a solid containingunderflow. Although the gravity settler may be any one of thosegenerally known in the art, the settler is preferably of a special typedeveloped for the present invention as hereinafter described withreference to FIG. 2.

The overflow essentially free of insoluble mateial, is withdrawn fromseparation zone 23 through line 24 and introduced into a recovery zone25 for recovering promoter liquid and various fractions of the coalextract. The recovery zone 25 may be comprised of one or morefractionators to distill various fractions from the product. Asparticularly described, the recovery zone is operated to recover a firstfraction having 5 percent and 95 percent volume distillationtemperatures of from 425 to 500 F. which is to be used as the promoterliquid for enhancing and promoting separation i of solid material fromthe coal liquefaction product; a second fraction (500600 F) which may beemployed as a distillate fuel blendstock; a third fraction (600- 900 F)a portion of which may be used as the coal liquefaction solvent in line12 and a further portion thereof recovered as product and a residualproduct 900 F) of low ash and reduced sulfur content which may be usedas a fuel or subjected to further treatment. The promoter liquidrecovered in the: recovery zone is admixed with the liquefaction productin line 17 and makeup may be provided through line 26.

The underflow containing dispersed insoluble material withdrawn fromseparation zone 23 through line 31 is introduced into a stripping zone32 wherein material boiling, below about 900 F is stripped therefrom andintroduced into the recovery zone 25 through line 33. The ash richstripper bottoms in line 34 may then be subjected to calcination orcoking. Alternatively, part of the stripper bottoms may be used asfeedstock to a partial oxidation process for producing hydrogen. As afurther alternative a portion of the stripper bottoms may be used forplant fuel. These uses and others should be apparent to those skilled inthe art from the teachings herein. In accordance with the presentinvention, the stripper bottoms in line 34 contains from about percentto about percent, by weight, of the MAF coal. In addition the coalproduct (the product recovered from zones 16 and 25, excludingliquefaction solvent and promoter liquid contains less than 1 percentand preferably less than 0.05 percent, by weight, of insoluble material.

The gravity settler of the present invention which is preferably used inthe embodiment of FIG. 1 is described with reference to FIG. 2.

Referring now to FIG. 2, there is shown the preferred settler 100 of thepresent invention comprised of a cylindrical main body portion 101 anddished upper and lower heads 102 and 103, respectively. The main bodyportion 101 is provided with a feed inlet 104 which is positionedperpendicularly to the main axis of the vessel 100 at a central pointthereof. The upper head 102 is provided with an inclined overflow outlet105 and the lower head 103 is provided with an inclined underflow outlet106, both of which are inclined at an angle of approximately The settler100 is slanted at an angle with respect to horizonatal with thepreferred angle being from about 45 to about The mixture of coalliquefaction prodnet and promoter liquid is introduced into the settlerthrough inlet 104, with the essentially solid free overflow beingwithdrawn through overflow outlet 105 and the solid containing underflowbeing withdrawn without accumulation of ash and bitumens.

Although the settler of the present invention is particularly suited foruse with the deashing technique of the present invention, such a settlermay also be used 5 for gravity settling deashing by techniques otherthan those of the present invention.

The invention will be further described with respect to the followingexamples, but the scope of the invention is not to be limited thereby.Unless otherwise indi- 10 cated all parts and percentages are by weight.

All of the hydrotreated coal solutions used in the subsequent deashingexamples except No. 92 (40 percent coal and 60 percent solvent) wereprepared from a coal paste or suspension containing 30 wt. percentbitumi- 15 nous coal (Illinois No. 6) and wt. percent 600-900 F. coaltar distillate. This coal paste was fed along with hydrogen into anupflow, expanded bed catalytic reactor, containing a commerciallyavailable catalyst. The reactor was operated at temperatures andpressures in 0 the 750-850 F. and LOGO-2,000 psig range respec- 25 sureand an ash-rich liquid product was withdrawn.

This ash-rich liquid receiver product will hereinafter be referred to aseither a coal solution, ash-rich coal solution, or hydrogenated coalsolution.

Table 1 below is a summary of analytical inspection 30 data obtained forthe ash-rich coal solutions used in the solvent deashing examples, whichwill be cited subsequently.

Table 1 Analytical Date Summary of Coal Solutions Used in the SolventDeashing Examples Coal Solution Number Ash-Rich Coal Soln. AnalvticalData wt. 7? Sulfur 0. wt. Ash 2. wt. 7! Benzene lnsolublcs 8.

ll 36 38 2I 66 92 Table 2 below is a compilation of CharacterizationFactors on liquids used in the subsequent deashing examples. This indexis a measure of aromaticity and/or parafinicity.

Table 2 Aromaticity and/or Paratinicity of the Liquids Used in thcDeashing Examples Liquids Char. Factor 571-95'4 volume distillate F.Remarks A 9.4l 400-450 Coal Tar Distillate B 8. 425-500 Coal TarDistillate C 9. 403 Tetrahydronaphthalene D l 1. 425-500 DistillatePrepared from Kerosene The use of the inclined separator of the present1n- EXAMPLE I vention for deashing a coal liquefaction product has beenfound to be particularly advantageous. The use of a settler in ahorizontal position generally results in an accumulation of ash andheavy bitumens. The use of a tank in a vertical position prevents theaccumulation of such materials, but it provides less settling crosssectional area than that provided in a horizontal tank. The use of theinclined settler of the present invention provides efficient use of agiven diameter vessel for settling 300 grams of ash-rich coal solutionnumber 1 and 1,200 grams of liquid A were charged to a 2 litercylindrical stainless steel electrically heated rocking bomb. Bomb inmeasurements was 4.26 inches l.D. X 18 inches long on the straight side,and it was equipped with a A inch bottom drawoff valve. The contents ofthe bomb were rocked and heated to 500 F. over about a 30 minute period.Bomb contents were then allowed to settle vertically for about 4 hoursat 500 F. without any rocking.

At the end of the settling period, 150 grams of an ashrich underflowstream were withdrawn through the bottom valve. The remainder of thebombs contents were withdrawn through the bottom valve and this ash-leansolution was analyzed for ash content. The ash content of the ash-leansolution was 0.25 wt. percent which corresponds to an ash removal of 57percent.

This example illustrates the ineffectiveness of an aromatic type ofliquid; i.e., a characterization factor K below 9.75, notwithstandingthe use of a liquid to coal solution of 4:1.

EXAMPLE 2 300 grams of ash-rich coal solution number 11, and a blend of300 grams of liquid D and 900 grams of liquid B, were added to the 2liter rocking bomb described in example 1. The contents of the bomb wereheated with rocking to 500 F. over about a 30 minute period. Bombcontents were then allowed to settle vertically for about 4 hours at 500F. without any rocking.

At the end of the settling period, 258 grams of an ashrich underflowstream were withdrawn through the bottom valve. The remainder of thebombs contents were withdrawn through the bottom valve and this ash-leansolution was analyzed for ash content. The ash content of the ash-leansolution was 0.01 wt. percent, which corresponds to an ash removal of98+ percent.

This example illustrates the effectiveness of a liquid blend at apromoter to coal solution ratio of about 1:1.

EXAMPLE 3 A 1,500 ml. dimpled glass resin flask was used in theexperiment. The resin flask was outfitted with a four bladed turbineagitator, thermometer, a heating mantle, reflux condenser, and adropping funnel.

450 grams of ash-rich coal solution number 36 was added to the resinflask. Flask contents were then heated with mixing to 350 F. over abouta 30 minute period. 585 grams of liquid C were added dropwise over abouta 1 hour period. Agitation and a temperature of 350 F. were maintainedduring anti-solvent addition. The contents of the flask were agitatedfor an additional 30 minute period at 350 F. Agitation was stopped andthe flask contents were settled for 4.0 hours at 350 F.

750 grams of ash-lean overflow solution were pipeted from the resinflask and analyzed for ash content. The resin flask was disassembled andan ash-rich underflow solution was poured from the flask. Ash content ofthe ash-lean overflow solution was found to be 0.08 wt. percent, whichcorresponds to an ash removal of 94.7 percent.

This example illustrates the effectiveness of a liquid promoter of thepresent invention, in the absence of diluent, at a promoter liquid tocoal solution ratio of 1.3:1.

EXAMPLE 4 The equipment used in this experiment is identical to thatused in Example 3.

650 grams of ash-rich coal solution number 38 was charged to a 1,500 mlresin flask. The flask was heated with mixing to 350 F. over about a 30minute period. 350 grams of liquid D were added dropwise over a l hourperiod via a dropping funnel. Mixing and a flask internal temperature of350 F. were maintained during the addition. The flasks contents wereagitated at 350 F. for an additional 30 minute period. Agitation wasstopped and the contents of the flask were allowed to settle for 4 hoursat 350 F.

708 grams of ash-lean overflow solution were pipeted from the resinflask and subsequently analyzed for ash content. The resin flask wasthen disassembled and an ash-rich underflow solution was poured from theflask. Ash content of the ash-lean overflow solution was found to be0.03 wt. percent, which corresponds to a 98.7 percent ash removal.

This example illustrates the effectiveness of a liquid promoter of thepresent invention, in the absence of diluent, at a promoter liquid tocoal solution ratio of about 0.54:1.

EXAMPLE 5 The apparatus used in this experiment is identical to thatused in Example 3.

450 grams of ash-rich coal solution number 11 and 650 grams of liquid Bwere charged to a 1,500 ml resin flask. The mixture was heated to 350 F.with stirring over about a 30 minute period. grams of liquid D wereadded dropwise via a dropping funnel over about a 1 hour period, whilethe agitation and a 350 F. flask internal temperature was maintained.The contents of the flask were then agitated at 350 F. for an additional30 minute period. Mixing was stopped and the flasks contents wereallowed to settle for 5 hours.

912 grams of ash-lean overflow solution was pipeted from the resin flaskand subsequently analyzed for ash content. The resin flask wasdisassembled and 268 grams of an ash-rich underflow solution was pouredtherefrom. Ash content of the ash-lean overflow solution was found to be0.05 wt. percent, which corresponds to a 96.4 percent ash removal.

This example illustrates the effectiveness of a liquid blend at a liquidto coal solution ratio of about 1.4:1.

EXAMPLE 6 The settler apparatus described with reference to FIG. 2 isused to deash ash-rich coal solution No. 21.

EXAMPLE 7 The apparatus described with reference to FIG. 2 is used todeash coal solution No. 92 using promoter liquid D. The conditions andresults are reported in the following Table.

Run 7A Run 78 Run 7C Coal 92 66 92 Liquid to Coal 0.40 0.45 0.50

The following laboratory runs indicate the difference between a promoterliquid of the present invention and hexane as a promoter liquid, hexanebeing a paraffmic liquid which does not have the boiling characteristicsof the liquid of the present invention.

Table Run 8A Run 813 Run 8C Coal Solution 92 92 92 Promoter liquidHexane Hexane D Wt. ratio of Promoter 0.40 0.50 0.50 liquid to CoalSolution Temp. F. 400 400 400 Pressure (psig) 100 100 Settling Time(hrs) 4.0 4.0 40 Ash content overflow 1.60 0.77 0.0l wt.% Ash removalwt. 59.2 810 997 +850F MAF components 39.2 50.3 26.8

present in underflow wt.% MAF coal fed The above indicates thedifference in effectiveness between hexane and the promoter liquid ofthe present invention.

EXAMPLE 9 In accordance with the present invention, in a typical run,based on 40 lbs. of coal feed in line 10 and 1.4 lbs. of hydrogen feedto the liquefaction zone, the net liquified coal product recovered inzone 16 and recovery zone is about 20 lbs; the gas make in theliquefaction zone is about 11 lbs; and the coal residual product in line34 is about 10 lbs., with about 4 lbs thereof being ash. This representsabout 99+ percent, by weight, ash removal, with MAF coal product lossbased on MAF coal feed, being about 18 percent, by weight.

EXAMPLE 10 Coal solution number 92 is deashed in the laboratory usingpromoter liquid D as follows:

The present invention is particularly advantageous in that insolublematerials can be separated from a coal liquefaction product withoutrequiring filtration. In addition, by proceeding in accordance with thepresent 5 invention ash and insoluble material separation can bemaximized with minimum loss of desired coal derived products and withmodest amounts of promoter liquid.

Although the prior art, in particular US. Pat. No. 3,607,716, disclosesa process for separating insoluble material from a coal liquefactionproduct, without filtration, by use of a fractionating solvent, such ashexane, as hereinabove described, the use of such light fractionatingsolvents require higher amounts of the solvent to effectively remove ashand such ash removal is accompanied by a loss of desired coal derivedproducts. In addition, such a process requires operating pressureshigher than those required in the present invention which increasesprocessing costs.

The present invention is also distinguishable from an extraction processin that the promoter liquid is not employed to extract a fraction of theliquid coal extract, but instead is employed to promote settling ofinsoluble material.

Numerous modifications and variations of the pres ent invention arepossible in light of the above teachings and, therefore, within thescope of the appended claims the invention may be practised other thanas particularly described.

What is claimed is:

l. A process for separating insoluble material from a coal liquefactionproduct produced from a coal feed and comprised of insoluble materialand carbonaceous matter dissolved in a coal liquefaction solvent,comprising:

introducing said liquefaction product and a liquid promoter into agravity settling zone to separate insoluble material by gravitysettling, said liquid promoter having a 5 volume percent distillationtem' perature of at least about 250 F. and a 95 volume percentdistillation temperature of at least about 350 F. and no greater thanabout 750 F., said liquid having a characterization factor (K) of atleast 9.75;

said liquid having a characterization factor greater than said coalliquefaction solvent;

said promoter liquid being added in an amount sufficient to promote andenhance gravity settling of insoluble material to produce an overflowessentially free of insoluble material; and

recovering from the settling zone a liquid overflow essentially free ofinsoluble material and a liquid underflow containing the insolublematerial.

2. The process of claim 1 wherein the weight ratio of liquid to coalsolution is from about 0.2:] to about 3.011.

3. The process of claim 2 wherein the 5 volume percent distillationtemperature of the liquid promoter is at least about 310 F.

4. The process of claim 2 wherein the liquid promoter is at least onemember selected from the group consisting of kerosene, kerosenefractions, middle distillates, light gas oils, gas oil fractions, heavynaphthas, white oils and white oil fractions from crude oils.

5. The process of claim 4 wherein the characterization factor of theliquid promoter has a value at least 0.25 higher than thecharacterization factor of the coal liquefaction solvent.

6. The process of claim 1 wherein the weight ratio of liquid to coalsolution is from about 0.3:1 to about 2.021.

7. The process of claim 6 wherein said promoter liquid istetrahydronaphthalene.

8. The process of claim 1 wherein said liquid has a characterizationfactor of at least 1 1.0.

9. The process of claim 8 wherein said gravity settling is effected at atemperature from about 300 F. to about 600 F. and a pressure from aboutpsig to about 500 psig.

10. The process of claim 8 wherein the promoter liquid is a fractionhaving a volume percent distillation temperature of at least about 425F. and a 95 volume percent distillation temperature of no greater thanabout 500 F.

11. The process of claim 1 wherein the liquid promoter is a kerosenefraction having a characterization factor of about 1 1.9 and a 5 volumepercent distillation temperature of no less than 425 F. and a 95 volumedistillation temperature of no greater than about 500 F.

12. The process of claim 11 wherein the weight ratio of liquid to coalsolution is from about 0.3:1 to about :1.

13. A process for separating insoluble material from a coal liquefactionproduct produced from a coal feed and comprised of insoluble materialand carbonaceous matter dissolved in a coal liquefaction, solvent,comprising:

effecting said separation in a gravity settling zone in the presence ofa liquid promoter of a hydrocarbon mixture, said liquid promoter havinga 5 volume percent distillation temperature of at least about 250 F anda 95 volume percent distillation temperature of at least about 350 F andno greater than about 750 F, said liquid promoter being at least onemember selected from the group consisting of kerosene, kerosenefractions, middle distillates, light gas oils, gas oil fractions, heavynaphthas, white oils and white oil fractions from crude oils,

and having a characterization factor (K) of at least said liquid havinga characterization factor greater than said coal liquefaction solvent,the liquid promoter to coal liquefaction product weight ratio being fromabout 0.2:1 to about 3.0:1, said ratio being an amount which produces anessentially insoluble material free overflow from said gravity settlingzone and a net coal product from said coal feed containing less thanabout 0.05 percent, by weight, insoluble material and an underflow whichcontains the insoluble material, said underflow containing no greaterthan about 40 percent, by weight, of the moisture ash free coal as anash free 850 F+ fraction.

14. The process of claim 13 wherein said 5 volume percent distillationtemperature is at least about 400 F.

15. The process of claim 14 wherein said promoter liquid is a kerosenefraction having a characterization factor of about 11.9, a 5 volumepercent distillation temperature of at least about 4250 F., and a 95volume percent distillation temperature of no greater than about 500 F.

16. The process of claim 15 wherein said settling zone is operated at atemperature from about 300 F to about 600 F and at a pressure from about0 psig to about 500 psig.

17. The process of claim 16 wherein said underflow contains no greaterthan about 25 percent, by weight, of the moisture ash free coal as anash free +850 F. fraction.

18.The process of claim 17 wherein said promoter liquid to coalliquefaction product weight ratio is from about 0.411 to about 06:1.

19. The process of claim 13 wherein underflow is withdrawn from saidsettling zone at a rate of from about 20 to about 25 wt. percent of thetotal of liquefaction product and promoter liquid introduced into thesettling zone.

20. The process of claim 13 wherein the liquid promoter has acharacterization factor of at least about 11.0.

21. The process of claim 20 wherein the promoter liquid has a volumepercentdistillation temperature of no greater than about 600 F.

22. The process of claim 20 and further comprising: stripping promoterliquid and components boiling up to about 900 F. from said underflow.

23. The process of claim 20 wherein the promoter liquid is a fractionhaving a 5 volume percent distillation temperature of at least about 425F. and a 95 volume percent distillation temperature of no greater thanabout 500 F.

24. The process of claim 13 wherein the characterization factor of theliquid promoter has a value at least 0.25 higher than thecharacterization factor of the coal liquefaction solvent.

25. A process for separating insoluble material from a coal liquefactionproduct produced from a coal feed and comprised of insoluble materialand carbonaceous matter dissolved in a coal liquefaction solvent,comprising:

a. separating from the coal liquefaction product at least thosecomponents boiling up to about the 95 volume percent distillationtemperature of the liquid promoter hereinafter defined in step (b);

b. introducing the coal liquefaction product from step (a) and a liquidpromoter into a gravity settling zone, said liquid promoter having a 5volume percent distillation temperature of at least about 250 F. and a95 volume percent distillation temperature of at least about 350 F. andno greater than about 750 F., said liquid having a characterizationfactor (K) of at least about 9.75, said liquid having a characterizationfactor K greater than said coal liquefaction solvent and being presentin an amount sufficient to promote and enhance gravity settling ofinsoluble material to produce a net coal product from said coal feedcontaining less than about 0.1 percent, by weight, insoluble materialand a coal residue con taining no greater than about 40 percent, byweight, of the MAP coal feed as an ash free +850 F. fraction;

0. withdrawing a liquid overflow essentially free of insoluble materialand a liquid underflow contain ing said coal residue from the gravitysettling zone;

d. separating the promoter liquid from the liquid overflow; and

e. passing separated promoter liquid from step (d) to step (b).

26. The process of claim 25 wherein the liquid promoter has acharacterization factor of at least about 1 1.0.

27. The process of claim 25 wherein in the liquid promoter is at leastone member selected from the group consisting of kerosene, kerosenefractions, middle distillates, light gas oils, gas oil fractions, heavynaphthas, white oils and white oil fractions from crude oils.

28. The process of claim 27 wherein the promoter liquid has a 5 volumepercent distillation temperature of at least about 310 F.

29. The process of claim 28 wherein said gravity settling is effected ata temperature from about 300 F to about 600 F and a pressure from about0 psig to about 500 psig.

30. The process of claim 29 wherein said liquid is a kerosene fractionhaving a characterization factor of about 1 1.9, a 5 volume percentdistillation temperature of no less than about 425 F. and a volumepercent distillation temperature of no greater than about 500 F.

31. The process of claim 27 wherein the characterization factor of theliquid promoter has a value at least 0.25 higher than thecharacterization factor of the coal liquefaction solvent.

3 a UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No.3,856,675 Dated December 24, 1974 Inventor(s) MORGAN C. SZE ET AL It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

' In the specification columnZ line 4 the formula (K) should read asfollows:

' Signed and Sealed this Tleenty-tltird Day Of December I980 [SEAL]Attest:

SIDNEY A. DIAMOND Attestt'ng Ojficer Commissioner of Patents andTrademarks

1. A PROCESS FOR SEPARATING INSOLUBLE MATERIAL FROM A COAL LIQUEFACTIONPRODUCT PRODUCED FROM A COAL FEED AND COMPRISED OF INSOLUBLE MATERIALAND CARBONACEOUS MATTER DISSOLVED IN A COAL LIQUEFACTION SOLVENT,COMPRISING: INTRODUCING SAID LIQUEFACTION PRODUCT AND A LIQUID PROMOTERINTO A GRAVITY SETTLING ZONE TO SEPARATE INSOLUBLE MATERIAL BY GRAVITYSETTLING, SAID LIAQUID PROMOTER HAVING A 5 VOLUME PERCENT DISTILLATIONTEMPERATURE OF AT LEAST ABOUT 250*F. AND A 95 VOLUME PERCENTDISTILLATION TEMPERATURE OF AT LEAST ABOUT 350*F. AND NO GREATER THANABOUT 750*F., SAID LIQUID HAVING A CHARACTERIZATION FACTOR (K) OF ATLEAST 9.75; SAID LIQUID HAVING A CHARACTERIZATION FACTOR GREATER THANSAID COAL LIQUEFACTION SOLVENT; SAID PROMOTER LIQUID BEING ADDED IN ANAMOUNT SUFFICIENT TO PROMOTE AND ENHANCE GRAVITY SETTLING OF INSOLUBLEMATERIAL TO PRODUCE AN OVERFLOW ESSENTIALLY FREE OF INSOLUBLE MATERIAL;AND RECOVERING FROM THE SETTLING ZONE A LIQUID OVERFLOW ESSENTIALLY FREEOF INSOLUBLE MATERIAL AND A LIQUID UNDERFLOW CONTAINING THE INSOLUBLEMATERIAL.
 2. The process of claim 1 wherein the weight ratio of liquidto coal solution is from about 0.2:1 to about 3.0:1.
 3. The process ofclaim 2 wherein the 5 volume percent distillation temperature of theliquid promoter is at least about 310* F.
 4. The process of claim 2wherein the liquid promoter is at least one member selected from thegroup consisting of kerosene, kerosene fractions, middle distillates,light gas oils, gas oil fractions, heavy naphthas, white oils and whiteoil fractions from crude oils.
 5. The process of claim 4 wherein thecharacterization factor of the liquid promoter has a value at least 0.25higher than the characterization factor of the coal liquefactionsolvent.
 6. The process of claim 1 wherein the weight ratio of liquid tocoal solution is from about 0.3:1 to about 2.0:1.
 7. The process ofclaim 6 wherein said promoter liquid is tetrahydronaphthalene.
 8. Theprocess of claim 1 wherein said liquid has a characterization factor ofat least 11.0.
 9. The process of claim 8 wherein said gravity settlingis effected at a temperature from about 300* F. to about 600* F. and apressure from about 0 psig to about 500 psig.
 10. The process of claim 8wherein the promoter liquid is a fraction having a 5 volume percentdistillation temperature of at least about 425* F. and a 95 volumepercent distillation temperature of no greater than about 500* F. 11.The process of claim 1 wherein the liquid promoter is a kerosenefraction having a characterization factor of about 11.9 and a 5 volumepercent distillation temperature of no less than 425* F. and a 95 volumedistillation temperature of no greater than about 500* F.
 12. Theprocess of claim 11 wherein the weight ratio of liquid to coal solutionis from about 0.3:1 to about 2.0:1.
 13. A process for separatinginsoluble material from a coal liquefaction product produced from a coalfeed and comprised of insoluble material and carbonaceous matterdissolved in a coal liquefaction, solvent, comprising: effecting saidseparation in a gravity settling zone in the presence of a liquidpromoter of a hydrocarbon mixture, said liquid promoter having a 5volume percent distillation temperature of at least about 250* F and a95 volume percent distillation temperature of at least about 350* F andno greater than about 750* F, said liquid promoter being at least onemember selected from the group consisting of kerosene, kerosenefractions, middle distillates, light gas oils, gas oil fractions, heavynaphthas, white oils and white oil fractions from crude oils, and havinga characterization factor (K) of at least 9.75, said liquid having acharacterization factor greater than said coal liquefaction solvent, theliquid promoter to coal liquefaction product weight ratio being fromabout 0.2:1 to about 3.0:1, said ratio being an amount which produces anessentially insoluble material free overflow from said gravity settlingzone and a net coal product from said coal feed containing less thanabout 0.05 percent, by weight, insoluble material and an underflow whichcontains the insoluble material, said underflow containing no greaterthan about 40 percent, by weight, of the moisture ash free coal as anash free 850* F+ fraction.
 14. The process of claim 13 wherein said 5volume percent distillation temperature is at least about 400* F. 15.The process of claim 14 wherein said promoter liquid is a kerosenefraction having a characterization factor of about 11.9, a 5 volumepercent distillation temperature of at least about 4250* F., and a 95volume percent distillation temperature of no greater than about 500* F.16. The process of claim 15 wherein said settling zone is operated at atemperature from about 300* F to about 600* F and at a pressure fromabout 0 psig to about 500 psig.
 17. The process of claim 16 wherein saidunderflow contains no greater than about 25 percent, by weight, of themoisture ash free coal as an ash free +850* F. fraction.
 18. The processof claim 17 wherein said promoter liquid to coal liquefaction productweight ratio is from about 0.4:1 to about 0.6:1.
 19. The process ofclaim 13 wherein underflow is withdrawn from said settling zone at arate of from about 20 to about 25 wt. percent of the total ofliquefaction product and promoter liquid introduced into the settlingzone.
 20. The process of claim 13 wherein the liquid promoter has acharacterization factor of at least about 11.0.
 21. The process of claim20 wherein the promoter liquid has a 95 volume percent distillationtemperature of no greater than about 600* F.
 22. The process of claim 20and further comprising: stripping promoter liquid and components boilingup to about 900* F. from said underflow.
 23. The process of claim 20wherein the promoter liquid is a fraction having a 5 volume percentdistillation temperature of at least about 425* F. and a 95 volumepercent distillation temperature of no greater than about 500* F. 24.The process of claim 13 wherein the characterization factor of theliquid promoter has a value at least 0.25 higher than thecharacterization factor of the coal liquefaction solvent.
 25. A processfor separating insoluble material from a coal liquefaction productproduced from a coal feed and comprised of insoluble material andcarbonaceous matter dissolved in a coal liquefaction solvent,comprising: a. separating from the coal liquefaction product at leastthose components boiling up to about the 95 volume percent distillationtemperature of the liquid promoter hereinafter defined in step (b); b.introducing the coal liquefaction product from step (a) and a liquidpromoter into a gravity settling zone, said liquid promoter having a 5volume percent distillation temperature of at least about 250* F. and a95 volume percent distillation temperature of at least about 350* F. andno greater than about 750* F., said liquid having a characterizationfactor (K) of at least about 9.75, said liquid having a characterizationfactor K greater than said coal liquefaction solvent and being presentin an amount sufficient to promote and enhance gravity settling ofinsoluble material to produce a net coal product from said coal feedcontaining less than about 0.1 percent, by weight, insoluble materialand a coal residue containing no greater than about 40 percent, byweight, of the MAF coal feed as an ash free +850* F. fraction; c.withdrawing a liquid overflow essentially free of insoluble material anda liquid underflow containing said coal residue from the gravitysettling zone; d. separating the promoter liquid from the liquidoverflow; and e. passing separated promoter liquid from step (d) to step(b).
 26. The process of claim 25 wherein the liquid promoter has acharacterization factor of at least about 11.0.
 27. The process of claim25 wherein in the liquid promoter is at least one member selected fromthe group consisting of kerosene, kerosene fractions, middledistillates, light gas oils, gas oil fractions, heavy naphthas, whiteoils and white oil fractions from crude oils.
 28. The process of claim27 wherein the promoter liquid has a 5 volume percent distillationtemperature of at least about 310* F.
 29. The process of claim 28wherein said gravity settling is effected at a temperature from about300* F to about 600* F and a pressure from about 0 psig to about 500psig.
 30. The process of claim 29 wherein said liquid is a kerosenefraction having a characterization fActor of about 11.9, a 5 volumepercent distillation temperature of no less than about 425* F. and a 95volume percent distillation temperature of no greater than about 500* F.31. The process of claim 27 wherein the characterization factor of theliquid promoter has a value at least 0.25 higher than thecharacterization factor of the coal liquefaction solvent.